Dipper door latch with locking mechanism

A dipper for a mining machine, said dipper comprising:

• a dipper body defining a material discharging opening;
• a dipper door coupled to said dipper body adjacent said discharging opening for pivotal movement relative to said dipper body between a closed position and an opened position;
• a first latch including a first bar, a first member having a recess for receiving the first bar, and a second member coupled to the first member, the first member being pivotable between a locked position and an unlocked position, the second member being pivotable between a locked position and an unlocked position, the second member including a second bar, wherein pivoting the second member from the locked position to the unlocked position causes the first member to pivot from the locked position to the unlocked position;
• and
• a second latch releasably holding said second member in said locked position when said first member is in said locked position.

A dipper for a mining machine, the dipper comprising:

• a body including an opening;
• a door coupled to the body to selectively open and close the opening, the door being pivotable between an open position and a closed position;
• a latch mechanism for releasably securing the dipper door in the closed position, the latch mechanism including a bar and a latch for engaging the bar, the latch being moveable between a locked state and an unlocked state;
• a plunger moveable between a first position and a second position, such that, when the plunger is in the first position, the latch mechanism is biased toward the unlocked state and, when the plunger is in the second position, the latch mechanism is permitted to move toward the locked state;
• and
• a drive mechanism coupled to the plunger, the drive mechanism moving the plunger from the first position to the second position when the dipper door is near the closed position.